Green tea could also be beneficial for preventing the devastating event, caused when a blood vessel in or serving the brain is either blocked or bursts.

Their study looked at the beverage habits of more than 83,000 healthy adults, aged 45 to 74, whose health was tracked for 13 years on average.

They found that people who drank at least one cup of coffee a day had about a 20 per cent lower risk of stroke, compared to those who rarely drank it. To get an equivalent effect, about four cups of green tea a day were required.

The drinks had a greater effect on reducing the chance of haemorrhagic (burst blood vessel) stroke. Those who drank at least one cup of coffee or two cups of green tea daily had a 32 per cent lower risk of this type of event.

All results were adjusted to take into account differences between the groups in age composition, gender, smoking, alcohol, weight, diet and exercise.

Dr Yoshihiro Kokubo, lead author of the study, published in the journal Stroke, said: “The regular action of drinking tea, coffee, largely benefits cardiovascular health because it partly keeps blood clots from forming."

Their results for coffee were similar to that of ‘study of studies’, presented at a European conference last May, which found that one to three cups a daily was associated with a 14 per cent reduction.

For three to six cups, there appeared to be a similar although weaker association, but there was no benefit from drinking six or more.

Exactly why coffee and green tea appears to lower stroke risk is unclear, although antioxidants are thought to be at work.

However, the science is by no means cut and dried. Caffeine raises blood pressure, and there have been indications that too much coffee can raise stroke risk because of this.

Dr Dale Webb, from the Stroke Association said: “We welcome this study which suggests that the benefits of antioxidants in coffee and green tea may offset the potential harm from caffeine.